Hyperprolactinemia in systemic lupus erythematosus?

Circulating prolactin level in Juvenile Systemic Lupus Erythematosus and its correlation with disease activity: a case control study

BACKGROUND

The linkage between prolactin (PRL) and systemic lupus erythematosus (SLE) is still vague. Determination of serum levels of prolactin to reveal its role in patients with SLE is the aim of the study.

METHODS

This is a case-control study performed on 40 children with SLE and 40 age- and sex-matched controls. Cases were further subdivided according to disease activity into mild, moderate, and severe groups using the SLEDAI (Systemic Lupus Erythematosus Disease Activity Index) score. Serum prolactin levels were assayed by ELISA (enzyme-linked immunosorbent assay).

RESULTS

prolactin level was significantly higher in SLE patients (17.3 ± 6.6 µg/L) than in controls (13.5 ± 5.3 µg/L) (P value = 0.005). Although the prolactin level was highest in severe cases (19.3 ± 7.7 µg/L), followed by moderate cases (17.0 ± 5.3 µg/L), and lowest in mild cases (14.0 ± 6.2 µg/L), the variance between the 3 groups was not statistically significant (P value = 0.212). A significant positive correlation between prolactin level and SLEDAI score was detected (r = 0.368) (P value = 0.019). Hyperprolactinemia was found in 8 patients (20%) but not in controls; 4 out of 8 patients with hyperprolactinemia (50%) showed neurological manifestations compared to only 3 out of 32 patients with a normal prolactin level (9.4%) (P value = 0.007).

CONCLUSION

A relationship between serum prolactin levels and juvenile SLE disease was detected. Neurological manifestations were more prevalent among SLE patients with hyperprolactinemia.

Circulating prolactin level in systemic lupus erythematosus and its correlation with disease activity: a meta-analysis

Objective

This study aimed to evaluate the relationship between circulating prolactin level and systemic lupus erythematosus (SLE), and to establish a correlation between plasma/serum prolactin levels and SLE activity.

Methods

We performed a meta-analysis comparing the plasma/serum prolactin levels in patients with SLE to controls, and examined correlation coefficients between circulating prolactin level and SLE disease activity.

Results

Twenty-five studies with a total of 1056 SLE patients and 426 controls were included. Prolactin levels were significantly higher overall in the SLE group than in the control group (standardized mean difference (SMD) = 0.987, 95% CI = 0.512–1.463, p = 4.7 × 10−5). Stratification by ethnicity showed significantly elevated prolactin levels in the SLE group in Asian, Latin American, and mixed populations (SMD = 0.813, 95% CI = 0.137–1.490, p = 0.018; SMD = 0.981, 95% CI = 0.307–1.655, p = 0.004; SMD = 1.469, 95% CI = 0.443–2.495, p = 0.005, respectively), but not in the European population. Subgroup analysis by sample size showed significantly higher prolactin levels in the SLE group by small ( n < 30) and large sample numbers ( n > 30). Meta-analysis of correlation coefficients showed a significantly positive correlation between circulating prolactin level and SLE activity (correlation coefficient = 0.379, 95% CI = 0.026–0.487, p = 4.0 × 10−9). Circulating prolactin levels were positively associated with SLE activity in European, Asian, and mixed populations (SMD = 0.532, 95% CI = 0.443–0.609  p < 1.0 × 10−8; SMD = 0.427, 95% CI = 0.240–0.583, p = 2.4 × 10−5; SMD = 0.433, 95% CI = 0.212–0.591, p = 2.7 × 10−5, respectively).

Conclusions

Our meta-analysis demonstrated that circulating prolactin levels are higher in patients with SLE, and that a significantly positive correlation exists between prolactin levels and SLE activity.

Pregnancy outcome in systemic lupus erythematosus (SLE) is improving: Results from a case control study and literature review

OBJECTIVES

For women who suffer from systemic lupus erythematosus (SLE), pregnancy can be a concern, placing the mother and fetus at risk. Our objectives were to assess the risk of adverse pregnancy outcome, disease flares, fertility rate, and co-morbidities in SLE women compared to healthy controls. We also systematically reviewed the literature available on pregnancy outcome in SLE to compare our results to other published data. Our hypothesis was that pregnancy outcome in SLE is improving over time.

METHODS

A case-control study comparing self-report of the above-mentioned parameters in SLE (N=108) vs healthy controls or patients with non-inflammatory musculoskeletal (MSK) disorders (N=134) was performed. Data were collected using a self-administered questionnaire. Proportions, means and odds ratios were calculated. We searched and quantified the literature on pregnancy outcome, lupus reactivation and fertility rate. Data were summarized and presented in mean % ± SEM and median % with interquartile range (IQR).

RESULTS

Gynecological history, fertility rate and age at first pregnancy in SLE patients were comparable to controls. Eighteen percent of SLE patients reported a flare and 18% reported an improvement of symptoms during pregnancy. Twenty-four percent of lupus patients had at least one preterm delivery vs 5% in controls (OR =8.32, p = 0.0008), however other pregnancy outcomes (miscarriage, therapeutic abortion, stillbirth and neonatal death rate) did not differ between the groups. Thyroid problems were reported to be more likely in SLE patients (p = 0.02), but the prevalence of other co-morbidities was similar to controls. A literature review demonstrated that fertility was not affected in SLE patients. Lupus reactivations are common during pregnancy (36.5% ± SEM 3.3%). Most agreed that SLE pregnancies had more fetal loss (19.5% ± SEM 1.6%) and preterm births (25.5% ± SEM 2.2%) when compared to the general population. Over time, the rate of SLE peripartum flares has improved (p = 0.002) and the proportion of pregnancies resulting in live birth has increased (p = 0.024). The frequency of fetal death has not significantly changed. Our findings from the case-control study were, in general, consistent with the literature including the frequency of fetal death, neonatal death, live births and pregnancy rate.

CONCLUSION

Prematurity (25.5% ± SEM 2.2%) and fetal death (19.5% ± SEM 1.6%) in SLE pregnancy are still a concern. However, new strategies with respect to pregnancy timing and multidisciplinary care have improved maternal and fetal outcome in SLE.

Effect of prolactin on lymphocyte activation from systemic lupus erythematosus patients

The aim was to explore the role of prolactin (PRL) in the lymphocyte activation process in systemic lupus erythematosus (SLE) patients in an in vitro model. Peripheral blood mononuclear cells (PBMCs) were isolated from SLE patients and healthy individuals. The mRNA for PRL and its receptor obtained by standard techniques, with an appropriate primer, were subjected to polymerase chain reaction (PCR) and visualized. The PBMCs were cultured with (a) medium alone as a negative control, (b) unspecific mitogen as a positive control, (c) PRL alone, (d) mitogen plus PRL, (e) mitogen plus antibody anti-PRL, and (f) mitogen plus a nonrelated antibody. Then CD69 and CD154 were determined by flow cytometry analysis. Twelve inactive and 15 active SLE patients were studied. Twenty-five percent of the active patients displayed hyperprolactinemia. Under basal conditions CD69 expression was associated with disease activity. The PBMCs activated in vitro were capable of producing and secreting PRL, measured by mRNA and Nb2 assay. In a similar way, the mRNA for the PRL receptor was visualized. Cells from SLE patients cultivated with PRL alone did not display increased CD69 and CD154 expression. The addition of PRL to the unspecific stimulated culture does not have an additive effect. In contrast, the addition of antibodies against PRL in order to block the autocrine PRL resulted in a striking reduction of CD69 and CD154 expression.

Selected acute phase proteins and interleukin-6 in systemic lupus erythematosus patients treated with low doses of quinagolide

The relationship between endocrine regulation and immune system has recently become the subject of intense investigations. The objective of this study was to determine the extent of selected serum acute phase proteins (APP), IL-6 and Systemic Lupus Erythematosus Disease Activity Index (SLEDAI) involvement in systemic lupus erythematosus (SLE) patients during quinagolide therapy. A further aim of this study was to evaluate the relationships between the above mentioned parameters. In 25 SLE patients treated with a low dose of quinagolide (12.5-50 microg per day) and in 25 healthy persons who constituted the control group, serum concentration of C-creative protein (CRP), alpha-1-antitripsin (AAT), ceruloplasmin (CER), IL-6 and prolactin (PRL) were estimated at entry and in patients after 3 months of treatment. Moreover, SLEDAI score was calculated at entry and after 3 months of therapy with quinagolide. IL-6 and PRL levels were significantly higher in SLE group whereas the concentrations of CRP, AAT and CER were higher than in the controls, but without statistical significance. After 3 month therapy statistically significant decrease of serum level of IL-6 and PRL was revealed. Statistically significant lower serum concentration of CER was also obtained after 3 months of therapy whereas serum CRP and AAT concentration was lower compared with the mean pretreatment level but the results did not reach statistical significance. A raised SLEDAI score at entry was significantly reduced after 3 month therapy and positive correlation with PRL level in examined group of patients with SLE was noted at entry. The decreased serum concentration of IL-6, APP and SLEDAI score observed during applied therapy with small dose of quinagolide confirms the hypothesis that quinagolide may become a valuable and safe drug in the therapy of patients with mild SLE.

Bone turnover markers, anterior pituitary and gonadal hormones, and bone mass evaluation using quantitative computed tomography in ankylosing spondylitis

The objective of this study was to determine bone mineral density (BMD) distribution in ankylosing spondylitis (AS) using quantitative computed tomography (QCT), to study bone turnover and anterior pituitary and gonadal hormonal axis in AS, and to look for correlations between BMD, bone remodeling markers and gonadal and anterior pituitary hormones. Forty-three male consecutive patients with AS were enrolled prospectively [mean (SD) age of 36.4 (11.3) years (range: 17-67) and mean disease duration of 6.8 (5.2) years (range: 0.4-19)]. Spine BMD was measured in all patients by QCT, and the results were compared to 29 male patients undergoing lumbar CT scan for sciatica. Bone turnover and anterior pituitary and gonadal axis were assessed in 29 patients, and the results were compared to 30 male healthy blood donors. The mean (SD) BMD was 127.7 mg/cm(3) (48.9) (range: 8.8-265.7) and 152.1 (25.3) (range: 34.2-190.4) in patients and controls, respectively (p = 0.018). Patients had lower serum levels of osteocalcin and higher levels of serum testosterone, luteinizing hormone (LH), and prolactin than controls with a significant statistical difference. There was a positive significant statistical correlation between BMD and chest expansion, Schober's test, C7-wall distance, and negative significant statistical correlation with age, disease duration, Bath Ankylosing Spondylitis Metrology Index (BASMI), Bath Ankylosing Spondylitis Radiology Index (BASRI), and serum prolactin. No correlation was observed between bone turnover parameters and AS symptomatic and structural severity indexes. BMD is lower with increasing age and late and severe disease. Decreased bone formation with normal resorption and increased levels of serum prolactin may be involved in its pathophysiology.

Pathogenesis of systemic lupus erythematosus

The exact patho-aetiology of systemic lupus erythematosus (SLE) remains elusive. An extremely complicated and multifactorial interaction among various genetic and environmental factors is probably involved. Multiple genes contribute to disease susceptibility. The interaction of sex, hormonal milieu, and the hypothalamo-pituitary-adrenal axis modifies this susceptibility and the clinical expression of the disease. Defective immune regulatory mechanisms, such as the clearance of apoptotic cells and immune complexes, are important contributors to the development of SLE. The loss of immune tolerance, increased antigenic load, excess T cell help, defective B cell suppression, and the shifting of T helper 1 (Th1) to Th2 immune responses leads to B cell hyperactivity and the production of pathogenic autoantibodies. Finally, certain environmental factors are probably required to trigger the disease.

Prolactin modulates the naive B cell repertoire

Prolactin is a peptide hormone produced by the anterior pituitary gland that is critical in lactation. Prolactin can also be produced by lymphocytes, and both B and T cells express prolactin receptors. These findings have suggested that prolactin has immunomodulatory functions. Studies in spontaneously autoimmune hosts have demonstrated a role for prolactin in augmenting autoreactivity. We chose to analyze prolactin effects on anti-DNA B cells in nonspontaneously autoimmune female BALB/c mice transgenic for the heavy chain of an anti-DNA antibody. Treatment with prolactin for 4 weeks induced a lupus-like phenotype with an increased number of transgene-expressing B cells, elevated serum anti-DNA antibody titers, and glomerular immunoglobulin deposits. Prolactin caused a decrease in the population of transitional B cells and an increase in mature follicular and marginal zone B cells. The DNA-reactive B cells had a follicular cell phenotype. Anti-DNA hybridomas demonstrated that prolactin alters selection of the naive B cell repertoire. The expansion and activation of anti-DNA B cells in prolactin-treated R4A-gamma2b BALB/c mice was dependent on the presence of CD4(+) T cells. Finally, treatment with prolactin was unable to break tolerance in R4A-gamma2b transgenic C57Bl/6 mice, suggesting that responsiveness of the immune system to prolactin is genetically determined.

Anti-prolactin autoantibodies in paediatric systemic lupus erythematosus patients

The aim of this study was to determine the frequency of anti-prolactin autoantibodies and the relationship among anti-prolactin autoantibodies, serum prolactin (PRL) levels and lupus activity in paediatric patients with systemic lupus erythematosus (SLE) using a transversal study. One-hundred and three consecutive paediatric SLE patients were tested for serum anti-PRL autoantibodies and PRL levels. Clinical disease activity was scored using the SLEDAI index. Anti-PRL autoantibodies were measured by means of gel filtration. The frequency of anti-PRL autoantibodies was 6.7% (7/103), on the basis of the amount of immunoreactive PRL eluted in molecular weight fraction corresponding to IgG (150 kDa). No anti-PRL autoantibodies were found in normoprolactinaemic patients. By contrast, 21.8% (7/32) hyperprolactinaemic patients (hPRL) had anti-PRL autoantibodies. There was a correlation between anti-PRL autoantibody and serum levels of PRL (r(s) = 0.98, P = 0.0001). Lupus activity was present in 64/103 (62.1%) patients, without a significant difference in the frequency of anti-PRL autoantibodies when compared to inactive lupus (7.8 vs 5.1%, P > 0.05). Higher levels of serum PRL were associated with lupus activity regardless of other variables (39.6% vs 17.9%, P = 0.05). Patients with anti-PRL autoantibodies had higher levels of serum PRL than those without anti-PRL autoantibody (41.85 vs 17.77 ng/ml, P = 0.01) and significantly different frequency of hPRL (100 vs 26%, r = 0.4531, P < 0.001). We have identified a subset of paediatric SLE patients with hPRL and anti-PRL autoantibodies. Anti-PRL autoantibodies were associated with hPRL state and antibody titres correlated positively with serum PRL levels. These data suggest that anti-PRL autoantibodies could be responsible for hPRL in a subset of SLE patients. An increase in serum PRL levels proved to be related to lupus activity, but there was no statistical relationship between anti-PRL autoantibodies and lupus activity.

Prolactin in human systemic lupus erythematosus

In the last decade, evidence has accumulated to support the hypothesis that both mild and moderate elevations of serum prolactin (PRL) participate in the clinical expression and pathogenesis of systemic lupus erythematosus (SLE). Hyperprolactinemia (HPRL) has been found in 20-30% of patients with SLE. HPRL seems to be associated with clinical activity of SLE during pregnancy. Although the relationship between HPRL and active SLE in non-pregnant patients is controversial, recent clinical and experimental studies support the potential role of prolactin (PRL) as a promoter of clinical activity and severity of SLE. Mild elevations of serum PRL secondary to microadenoma could trigger the onset of SLE in a subset of patients. Elevated PRL and interleukin (IL)-6 have been found in the urine of patients with active lupus nephritis and in cerebrospinal fluid (CSF) of patients with active central nervous system (CNS) SLE. PRL may therefore participate in the pathogenesis of lupus nephritis and cerebritis, and the presence of PRL may reflect an abnormal communication between the immune system and the neuroendocrine system in active SLE. Lymphocytes from patients with active SLE produce increased amounts of PRL, and this extrapituitary PRL may participate in aberrant immune processes in SLE. There is exciting new evidence that HPRL in SLE may be explained by stimulation of pituitary PRL secretion by cytokines. In addition, defects in peptidergic modulators and dopamine metabolism have been described in patients with SLE. The interactions between PRL, cytoquines, autoantibodies and organ involvement suggest that PRL participates in local and generalized immune and inflammatory processes and acts as a bridge between the neuroendocrine and immune systems in SLE. Understanding the interactions between these systems in SLE will help us to understand and treat this important autoimmune disease.

Enhanced serum prolactin (PRL) in patients with systemic lupus erythematosus: PRL levels are related to the disease activity

Recent accumulated evidence suggests that prolactin (PRL) is an important immunomodulator and plays a part in the pathogenesis of systemic lupus erythematosus (SLE). The current study assessed the frequency of hyperprolactinaemia in patients with SLE and its association with defined clinical manifestations or serological abnormalities. PRL levels were analysed in 60 patients with SLE including a follow-up of 20 patients, 18 patients with rheumatic autoimmune diseases other than SLE (AID) and in 47 normal healthy subjects (NHS) using ELISA. Clinical manifestations and disease activity (ECLAM) were recorded. Autoantibodies (anti-dsDNA, anti-CL) were determined by standard techniques. In all, 28.3% of the patients with SLE had raised serum PRL. Their PRL levels (17.4+/-15.1 ng/ml, P<0.0001) and those of patients with AID (13.1+/-10.3 ng/ml, P<0.001) were significantly higher compared to NHS (6.3+/-3.2 ng/ml). Anti-dsDNA (r(s) = 0.3, P = 0.04) and anti-CL antibody titres (IgG; r(s) = 0.3, P = 0.03) correlated with PRL level. Furthermore, elevated erytthrocyte sedimentation rate (ESR), anaemia, decrease in C3, fatigue, fever and renal involvement were associated with hyperprolactinaemia. These results were confirmed by follow-up examinations. Moderate hyperprolactinaemia is present in a subset of patients with SLE and serum PRL correlates with clinical and serological disease activity.

Detection of macroprolactinemia with the polyethylene glycol precipitation test in systemic lupus erythematosus patients with hyperprolactinemia

The objective of this study was to determine the diagnostic performance of the percentage of serum prolactin (PRL) precipitated with polyethylene glycol (PEG) for the detection of macroprolactinemia in systemic lupus erythematosus (SLE) patients with hyperprolactinemia. Serum samples from SLE patients were examined. Serum PRL was measured by immunoradiometric assay (IRMA) and samples with hyperprolactinemia (> 20 ng/ml) were submitted to PEG precipitation, gel filtration chromatography and affinity chromatography with protein-G sepharose. A comparative survey was used. Among 259 consecutive serum samples from SLE patients, PRL was > 20.1 ng/ml in 43 samples (16.6%). Gel filtration showed a predominant pattern of macroprolactinemia (> 100 kDa) in 14 (32.6%), a predominant pattern of monomeric PRL (23 kDa) in 27 (62.7%), and a variable pattern in two (4.7%). All sera with a predominant pattern of macroprolactinemia displayed anti-PRL autoantibodies by affinity chromatography for IgG. The best cut-off point for percentage of serum PRL precipitated with PEG for detection of macroprolactinemia was > or = 58.4%. Sensitivity and specificity were 100 and 96.6%, respectively. We can conclude that PEG precipitation is a convenient and simple procedure to screen for the presence of macroprolactinemia in sera from SLE patients. Precipitations > or = 58.4% are indicative of the presence of, and those < 50% the absence of, macroprolactinemia. However, samples with precipitations between 50 and 58.3% require gel filtration chromatography to characterize the predominant molecular form of PRL. Therefore, it is important to take these findings into account in future studies that aim to establish a relationship between PRL and disease activity in SLE.

Treatment of systemic lupus erythematosus with bromocriptine

Prolactin, a lactogenic hormone, is a cytokine and an important link between the immune and endocrine systems. Prolactin stimulated disease in autoimmune NZB/NZW mice. Treatment of the mice with the prolactin-lowering dopamine agonist, bromocriptine, suppressed anti-DNA and prolonged life spans. These findings have been applied to humans with systemic lupus erythematosus (SLE). An open-label study, a double blind study, and a study comparing bromocriptine to hydroxychloroquine provided evidence that bromocriptine therapy reduced flares and suppressed disease activity in SLE.

Bromocriptine in rheumatic and autoimmune diseases

BACKGROUND AND OBJECTIVES

Multiple lines of evidence support the concept that the anterior pituitary hormone prolactin has a pathogenic role in rheumatic and autoimmune diseases including, but not limited to, rheumatoid arthritis (RA), systemic lupus erythematosus (SLE), Reiter's syndrome, psoriatic arthritis, and uveitis. Conversely, the dopaminergic agonist bromocriptine appears to have therapeutic effects through suppression of pituitary prolactin secretion and, perhaps, through actions on peripheral dopamine receptors. This article reviews the experimental and clinical data supporting the therapeutic use of bromocriptine as a nonstandard or adjunctive therapy in rheumatic and autoimmune diseases.

METHODS

Data addressing the potential therapeutic role of bromocriptine in rheumatic and autoimmune diseases, as well as frequently associated comorbidities, was accumulated from the author's work, online literature search of the National Library of Medicine, and references from these identified publications.

RESULTS

There have been a number of clinical therapeutic trials using 2.5 to 30 mg of bromocriptine per day in a single or divided dose, which have shown efficacy with minimal side effects in the treatment of rheumatic and autoimmune diseases. In RA, bromocriptine administration has induced immunosuppression of several immune parameters and has been associated with improvements in morning stiffness, grip strength, numbers of swollen/painful joints, and the Health Assessment Questionnaire disability index. In two blinded studies, bromocriptine reduced the number of SLE flares and was as effective as hydroxychloroquine in reducing lupus disease activity indices, respectively. In case reports, bromocriptine has been used successfully in the treatment of Reiter's syndrome enthesopathy and psoriatic arthritis. The potential efficacy of bromocriptine in the treatment of uveitis and multiple sclerosis is suggested but remains to be verified.

CONCLUSIONS

Double-blind, placebo-controlled studies are limited, but clinical observations and trials support the use of bromocriptine as a nonstandard primary or adjunctive therapy in the treatment of recalcitrant RA, SLE, Reiter's syndrome, and psoriatic arthritis and associated conditions unresponsive to traditional approaches. Additional investigation is needed to verify this conclusion and extend preliminary results.

RELEVANCE

In patients with rheumatic and autoimmune diseases, bromocriptine may be a relatively safe and efficacious alternative therapy. Semin Arthritis Rheum 31:21-32.

Pregnancy in systemic lupus erythematosus

Systemic lupus erythematosus (SLE) is an autoimmune disease that predominantly affects women of reproductive age. Pregnancy and its outcome is a major concern to most SLE patients. Queries regarding the risk of disease flares during pregnancy, chance of fetal loss, and the safety of various drugs are often raised. With the improvement in the understanding of the pathogenesis of SLE and the judicious use of immunosuppressive drugs, better disease control can now be achieved and SLE patients should not be deprived of the opportunity for bearing children. Prepregnancy counselling and close collaboration with other specialists such as the obstetricians and the perinatologists is essential in optimising the maternal and fetal outcome in lupus pregnancies. In this review, important issues regarding the fertility rate, optimal timing of conception, risk of disease flares during lupus pregnancy, pregnancy course, fetal outcome, safety of various drugs used for disease control during pregnancy and lactation, and contraceptive advice are discussed.

Prolactin enhances the in vitro production of IgG in peripheral blood mononuclear cells from patients with systemic lupus erythematosus but not from healthy controls

OBJECTIVES

Recent evidence suggests that prolactin (PRL) plays a part in the pathogenesis of systemic lupus erythematosus (SLE). Because B cell hyperreactivity and autoantibodies are characteristic hallmarks of SLE, this study aimed at assessing the impact of this pituitary hormone on IgG production by stimulating peripheral blood mononuclear cells (PBMC) with PRL.

METHODS

PBMC from 11 patients with SLE assessed by the ECLAM score and eight healthy controls were incubated with PRL and cultured for seven days. IgG production was measured by enzyme linked immunosorbent assay (ELISA).

RESULTS

Spontaneous IgG production of SLE PBMC was significantly enhanced compared with that found in healthy controls. After PRL stimulation, the IgG concentrations of supernatants from SLE PBMC were significantly higher than those of unstimulated PBMC (median 394 ng/ml). Of note, the physiological concentration of PRL (20 ng/ml) induced IgG production more effectively (median 1139 ng/ml) than PRL at 100 ng/ml (median 1029 ng/ml). In contrast, preincubation with PRL did not stimulate IgG production in normal PBMC. A significant correlation between PRL induced IgG production and the disease activity (ECLAM) of the patients with SLE was seen. Moreover, the maximum amount of PRL induced IgG depended on the serum PRL concentrations of the patients with SLE.

CONCLUSIONS

The results suggest that PBMC from patients with SLE have an extraordinarily high susceptibility to PRL, showing the most striking effect at a concentration usually found in vivo. This indicates a potential role for mild hyperprolactinaemia in the pathogenesis of SLE, influencing both IgG production and disease activity.

Bromocriptine restores tolerance in estrogen-treated mice

Estrogen can modulate autoimmunity in certain models of systemic lupus erythematosus. Recently, we have shown that it can mediate survival and activation of anti-DNA B cells in a mouse transgenic for the heavy chain of a pathogenic anti-DNA antibody. To identify whether estrogen effects reflect increased prolactin secretion, we characterized B-cell autoreactivity in transgenic mice given both bromocriptine (an inhibitor of prolactin secretion) and estradiol. Treatment of mice with estradiol plus bromocriptine led to reduced titers of anti-DNA antibodies and diminished IgG deposition in kidneys compared with treatment with estradiol alone. However, mice treated with estradiol plus bromocriptine showed an expansion of transgene-expressing B cells and enhanced Bcl-2 expression, similar to those of estradiol-treated mice. We identified anergic high-affinity anti-DNA B cells in mice treated with estradiol plus bromocriptine, and we showed by molecular analysis of anti-DNA hybridomas that their B cells derive from a naive repertoire. Thus, the estradiol-induced breakdown in B-cell tolerance can be abrogated by bromocriptine, which induces anergy in the high-affinity DNA-reactive B cells. These studies demonstrate that some of the effects of estrogen on naive autoreactive B cells require the presence of prolactin and, thus, suggest potential therapeutic interventions in lupus.

Roles of prolactin and gonadotropin-releasing hormone in rheumatic diseases

PRL is capable of influencing immune responses and is a cytokine in all likelihood. Circulating PRL is elevated in a number of autoimmune diseases, and about 20% of SLE patients are hyperprolactinemic. The serum PRL concentration often does not reflect disease activity in SLE. The PRL-suppressing drug bromocriptine has been reported to benefit small numbers of patients with reactive arthritis and inflammatory eye disease, and bromocriptine may be beneficial in treating SLE. In NZB/NZW mice, bromocriptine was beneficial and prolonged life. Bromocriptine therapy favorably modified disease in human SLE. In a preliminary open-label study, SLE patients treated with bromocriptine for 6 months had significant improvement in disease activity. These responses were corroborated by masted therapeutic studies. Daily treatment with low-dose bromocriptine prevented lupus flares, and bromocriptine was as effective as hydroxychloroquine in treating active nonorgan-threatening disease. The reports of the efficacy of bromocriptine treatment of SLE are encouraging. Additional studies may confirm the findings reported in this review and may lead to further use of hormonal modification to treat lupus and other autoimmune diseases. For the present, it is important to understand that treatment with dopamine agonists such as bromocriptine is experimental and best confined to therapeutic trials. In the experience of the authors, bromocriptine should not be relied on to treat severe life-threatening autoimmune disease. If bromocriptine is used to treat SLE and is then discontinued, the patient should be observed carefully for rebound hyperprolactinemia and the development of a lupus flare. GnRH is produced by lymphocytes and exerts immunomodulatory actions. Thus, GnRH resembles a cytokine. GnRH can be shown to exert gender-restricted immune actions in vitro and in vivo. The authors' preliminary observations are consistent with the possibility that gender-related differences in expression of the GnRH receptor or in GnRH signal transducers may contribute to gender-related differences in immune responsiveness to GnRH. These differences in G proteins may contribute to the gender-related differences in immunity and expression of autoimmune disease.

Plasma homovanillic acid and prolactin in systemic lupus erythematosus

Prolactin (PRL) is an important immunoregulator and might have a role in the pathogenesis of systemic lupus erythematosus (SLE). The regulation of pituitary prolactin secretion is complex and involves a negative feedback process in the hypothalamus, in which dopamine plays the principal role. However, the main source of serum prolactin in lupus patients is still not clearly established. Since homovanillic acid (HVA), the principal metabolite of dopamine (DA), is removed from the brain into the blood, it would indirectly reflect DA metabolism. It is assumed that the turnover of a neurotransmitter can be determined through an analysis of its metabolites. The objective of this study was to analyse plasma samples from SLE patients to see if there were any alterations in neurally functioning DA through its principal metabolite, HVA. We also measured the levels of PRL and compared HVA and PRL with the clinical activity of the disease. Twenty-four SLE patients and fifteen healthy controls were studied. The investigation was done over a period of 3 months. The results of this study show significantly low levels of HVA in lupus patients compared to controls (P < 0.0001). This corresponds to a decrease in dopamine turnover. Hyperprolactinemia was observed in nine patients, and the average level of prolactin in lupus patients was higher than in healthy controls (P < 0.001). For the duration of the study, a significant percentage of variation was observed in the levels of HVA in the clinically active patients (P < 0.05) compared to inactive patients. When PRL was compared in these groups, throughout the study, no significant percentage of variation was observed. The relationship between HVA and PRL in healthy controls was r = 0.47, P = 0.08, and in patients was r = 0.04, P = 0.84. It is suggested that there is a probable association between plasma levels of HVA and PRL in the healthy controls and not in the SLE patients.

Anti-prolactin autoantibodies in systemic lupus erythematosus patients with associated hyperprolactinemia

Hyperprolactinemia has been found in a subset of systemic lupus erythematosus (SLE) patients. In order to explore whether antibodies to prolactin (PRL) play a role in SLE patients with associated hyperprolactinemia, we performed a cross-sectional study in which 259 consecutive SLE patients were tested for hyperprolactinemia and anti-prolactin autoantibodies. Forty-one (15.8%) had prolactin levels above the norm. The frequency of anti-PRL autoantibodies in hyperprolactinemia was 2/14 (14.3%). In the SLE patients with 'idiopathic hyperprolactinemia', 11/27 (40.7 %) had anti-PRL antibodies. The levels of serum PRL were significantly higher in patients with idiopathic hyperprolactinemia and anti-PRL autoantibody compared to the patients with idiopathic hyperprolactinemia who were anti-PRL autoantibody-negative. Patients with idiopathic hyperprolactinemia and anti-PRL autoantibody had relatively low SLE disease activity index (SLEDAI) scores and significantly different laboratory parameters compared to those with idiopathic hyperprolactinemia and no anti-PRL antibody. There was a significant correlation between titers of the anti-PRL autoantibody and serum PRL levels (rs = 0.98, P = 0.0001). These data suggest that anti-PRL antibodies could be the cause of hyperprolactinemia in a subset of SLE patients, especially those with particularly high serum prolactin levels with a diagnosis of 'idiopathic hyperprolactinemia'. The patients with anti-PRL antibody had fewer clinical manifestations and less serological activity, indicating that biological activity of PRL was attenuated by the autoantibody.